10.5 Detecting heap memory leaks

Free Pascal has a built in mechanism to detect memory leaks. There is a plug-in unit for the memory manager that analyses the memory allocation/deallocation and which prints a memory usage report after the program exits.

The unit that does this is called heaptrc. If you want to use it, you should include it as the first unit in you uses clause. Alternatively, you can supply the -gh switch to the compiler, and it will include the unit automatically for you.

After the program exits, you will get a report looking like this:

 Marked memory at 0040FA50 invalid
 Wrong size : 128 allocated 64 freed
   0x00408708
   0x0040CB49
   0x0040C481
 Call trace for block 0x0040FA50 size 128
   0x0040CB3D
   0x0040C481
The output of the heaptrc unit is customizable by setting some variables.

version 2.0 only: Output can also be customized using environment variables. You can find more information about the usage of the heaptrc unit in the Unit reference.